The present invention relates, in general, to vehicular and/or automotive steering devices and in particular to a dual hydraulic steering system for articulated transport vehicles.
While the vast majority of conventional transporting vehicles in utilization today comprises tractor-trailer combinations, utilizing conventional Ackerman steering assemblies, there has more recently been development and utilization of articulated type transporting vehicles which avoid utilization of this typical type of conventional steering. With such a vehicle, and the avoidance of conventional Ackerman steering, many maeuverability problems of the conventional vehicle are avoided. Articulated vehicles, for the most part, reduce the problems of conventional vehicles associated with getting stuck in mud, or becoming entrapped in loose earth, sand, bog, snow, or piles of litter often encountered in refuse dumps. Additionally, articulated vehicles frequently have the ability to "walk out" of tire track ruts and soft terrain, and, due to their articulation, have smaller and sharper turning radii and improved handling, to mention but a few advantages.
The conventional Ackerman steering mechanisms provide difficulties in other areas also. The reliance upon the two or more front wheels of the front cab portion of the conventional tractor-trailer transport vehicle requires swivelling in order to change the direction of the vehicle. The vast amount of mechanical cooperating elements in which pumps, reservoirs, and hydraulic components are combined with energy wasting mechanical linkages, extraordinary and often complex, gear assemblies and the like, further increase the power consumption of such conventional steering units. Unless increased power is consumed through the addition of a power steering unit, such conventional type steering on transport vehicles, often provide difficult-to-handle and somewhat overwhelming steering control problems.
As an alternative to these conventional tractor-trailer configurations, the articulated vehicles mentioned above have been utilized, as disclosed in Kamner U.S. Pat. No. 3,515,235. It should be realized, however, that the Kamner invention depends upon a combination of both conventional Ackerman and hydraulic-articulated steering means to somewhat reduce the turning radius and improve the maneuverability in such vehicles. Similarly, articulated vehicles, such as those disclosed in Robinson et al., U.S. Pat. Nos. 2,933,143; Starkey, 2,271,808; Lindell, 3,771,141 and McGee, 3,834,480, all describe various interpretations or articulated steering systems.
While the advantages of articulated vehicles utilizing articulated steering means are obtained through many of these references, their reliance upon single powered steering systems offers disadvantages to these inventions. None of these inventions, for example, utilizes a totally hydraulic articulated steering system with an equivalent total hydraulic steering system for back-up, emergencies, and for supplementary additional steering power. Additionally, few if any of the references utilize a true and total hydraulic articulated steering system without dependence upon additional mechanical linkages to accomplish steering, and thus these references provide for systems in which mechanical linkage drag and power loss are still involved with the steering system.
Neither of the existing art inventions identified above provides for emergency steering or back-up steering power with a second system in case one system has a failure, nor discloses the use of the dual steering system in which both of the two steering systems provide more than normal steering power for the vehicle, imparting to the vehicle a more controllable steering system which is more reliable to its user.
It is thus an object of the present invention to provide a dual hydraulic steering system for articulated vehicles in which each component of the dual system provides for emergency steering or back-up steering power for the other component in case the first fails, or is associated with a telescoping hydraulic cylinder which fails.
It is also an object of the present invention to provide a steering system in which both components of the steering system are synchronized to operate effectively together, towards providing more than normal steering power for the vehicle in the absence of emergency situations, and which, at the same time, provides improved and more stable control of the vehicle.
Additionally, it is an object of the present invention to provide a dual steering system controlled by a common steering wheel in which each system either has totally independent power circuity directed to particular steering cylinders, or has independent power components which rely upon other shared hydraulic components to appropriately segregate the hydraulic operation of each, and accordingly provide the back-up, emergency, and auxiliary steering power outlined above.
It is further an object of this invention to provide a more reliable steering system for articulated vehicles which are equipped with warning devices to alert an operator in the event of system failure, while at the same time, providing safe hydraulic steering without mechanical linkages so as to reduce mechanical linkage drag and power loss. At the same time, it is an object of this invention to eliminate the need for steering axles which hinder performance and to provide this safe steering to an articulated vehicle, so as to enable such a vehicle to "walk through" soft terrain, steer more easily, to require less manual effort on the part of the operator, to improve the turning radius of the vehicle, and, in general, to improve the maneuverabiliyy of the vehicle and its associated load.
These and other objects of the invention will become apparent in light of the following disclosure.